1. Field of the Invention
The present invention relates to a dry etching method of a silicon compound film.
2. Description of the Related Art
As a conventional thin film transistor, there is, for example, a reverse-staggered type thin film transistor. In this reverse-staggered type thin film transistor, a gate electrode is provided on the upper surface of a substrate, and a gate insulating film is provided on the upper surface of the substrate including the gate electrode. In addition, a semiconductor thin film made of intrinsic amorphous silicon is provided on the upper surface of the gate insulating film, above the gate electrode. Moreover, ohmic contact layers made of n-type amorphous silicon are provided on both sides of the upper surface of the semiconductor thin film, and a source electrode and a drain electrode are provided on the upper surface of each ohmic contact layer.
In the method of forming the ohmic contact layer and the semiconductor thin film in the conventional thin film transistor described above, the intrinsic amorphous silicon film (semiconductor thin film formation film) and the n-type amorphous silicon film (ohmic contact layer formation film) formed on the upper surface of the gate insulating film are sequentially dry etched. In this case, sulfur hexafluoride (SF6) gas is used as an etching gas.
However, SF6 as the etching gas used in a conventional dry etching method such as described above has an extremely high warming potential of several thousand to several tens of thousands. Therefore, in recent years, SF6 has been regarded as a problem that contributes to global warming. Accordingly, the selection of an alternative gas replacing SF6 is an important issue.